Robert W. McGraw

The outcome of two-stage arthroplasty using a custom-made interval spacer to treat the infected hip

Sixty-one patients undergoing a two-stage revision of an infected hip using a prosthesis of antibiotic-loaded acrylic cement were followed for an average of 43 months. Twelve patients were excluded (3 died, 6 had no proven infection, and 2 no second stage). Only 1 patient was lost to follow-up evaluation from those included, for a retrieval rate of 98% for those still living. Of the remaining 48 patients, 3 had further sepsis: Two became reinfected with different organisms and 1 with the same organism, for an infection eradication rate of 94%. The other 45 had no clinical, laboratory, or radiographic evidence of infection. Thirty-seven patients (80%) had a Harris hip score greater than 80 or an improvement of at least 30 points.

The PROSTALAC functional spacer in two-stage revision for infected knee replacements

The PROSTALAC functional spacer is made of antibiotic-loaded acrylic cement but has a small metal-on-polythene articular surface. We have used it as an interim spacer in two-stage exchange arthroplasty for infected total knee replacement. PROSTALAC allows continuous rehabilitation between stages as it maintains good alignment and stability of the knee and a reasonable range of movement. It also helps to maintain the soft-tissue planes, which facilitates the second-stage procedure. We reviewed 45 consecutive patients, treated over a period of nine years. The mean follow-up was for 48 months (20 to 112). At final review, there was no evidence of infection in 41 patients (91%); only one had a recurrent infection with the same organism. There was improvement in the Hospital for Special Surgery knee score between stages and at final review. The range of movement was maintained between stages. Complications were primarily related to the extensor mechanism and stability of the knee between stages. Both of these problems decreased with refinement of the design of the implant. The rate of cure of the infection in our patients was similar to that using other methods. Movement of the knee does not appear to hinder control of infection.

Patient Satisfaction and Functional Status After Treatment of Infection at the Site of a Total Knee Arthroplasty with Use of the PROSTALAC Articulating Spacer

BACKGROUND Two-stage exchange arthroplasty remains the standard treatment of infection at the site of a total knee arthroplasty. The clinical and functional outcomes associated with the use of an articulating antibiotic spacer for two-stage revision for infection are not well established. We conducted a retrospective study to evaluate the outcomes associated with the use of the PROSTALAC articulating spacer between the first and second stages. METHODS Fifty-eight patients underwent two-stage revision total knee arthroplasty for infection between January 1997 and December 1999. Of these, fifty-four were alive at the time of follow-up and forty-seven were available for inclusion in the present retrospective study. In all patients, a prosthesis of antibiotic-loaded acrylic cement (the PROSTALAC system) was implanted during the first stage after débridement. The amount of osteolysis that occurred between the stages and the range of motion of the knee joint were measured. After two years of follow-up, outcomes were assessed with use of the WOMAC, Oxford-12, and SF-12 instruments as well as a satisfaction questionnaire. RESULTS At a minimum of two years (average, forty-one months) after revision arthroplasty, two patients (4%) had had a recurrence of infection. The amount of bone loss was unchanged between stages, and the range of movement of the knee improved from 78.2 degrees before the first stage to 87.1 degrees at two years. The average normalized WOMAC function and pain scores were 68.9 and 77.1, respectively; the average Oxford-12 score was 67.3; the average SF-12 mental and physical scores were 53.7 and 41.2, respectively; and the average satisfaction score was 71.7. CONCLUSION A revision operation for infection at the site of a total knee replacement with use of an articulating spacer was associated with reasonable function and satisfaction scores. These findings may be related to the articulating features of the PROSTALAC system, which permits full active movement of the knee in the early postoperative period.

Occlusion of arterial flow in the extremities at subsystolic pressures through the use of wide tourniquet cuffs

Tourniquet-induced peripheral neuropathy is at least partially attributable to excessive forces applied to the nerves beneath cuffs inflated to high pressures. Lowering the inflation pressure to the minimum necessary to obtain an effective arrest of blood flow distal to the tourniquet cuff should increase the safety of these systems. Tourniquet cuffs with widths varying from 4.5 cm to 80 cm were applied to the upper and lower extremities of 34 healthy, normotensive volunteers. Occlusion pressure for the arterial system under study was estimated by determining that level of cuff inflation at which the distal pulse became detectable by ultrasonic flowmetry. The occlusion pressure was inversely proportional to the ratio of tourniquet cuff width to limb circumference and was in the subsystolic range at a cuff width to limb circumference ratio above 0.5. Wide tourniquet cuffs can achieve an effective arrest of the regional arterial circulation at subsystolic pressures of inflation. Wide cuffs may reduce the risk of tourniquet-induced injury to underlying soft tissues by lowering the inflation pressure required to secure a bloodless field.

Arterial complications and total knee arthroplasty.

&NA; Arterial complications after total knee arthroplasty (TKA) are rare; however, the sequelae can be disastrous. Infection and the need for amputation or vascular reconstructive surgery are not uncommon. A thorough preoperative assessment can identify at‐risk patients, many, if not all, of whom have preexisting peripheral arterial disease. In the presence of peripheral arterial disease, the use of a tourniquet during TKA has been implicated in subsequent arterial complications. Following the guidelines that have been established regarding preoperative assessment, the role of the vascular surgeon, and the use of a tourniquet before and during TKA can assist the orthopaedic surgeon in assessing candidates for TKA and reducing the risk of arterial complications.

The extensile rectus snip exposure in revision of total knee arthroplasty

Revision of a total knee arthroplasty may require an extensile approach to permit a satisfactory exposure without compromising the attachment of the patellar tendon. It has been assumed that a rectus snip is a relatively benign form of release, but the effect of using this approach on function, pain and patient satisfaction is not known. From January 1997 to December 1999, 107 patients who underwent revision of total knee arthroplasty were followed up at a minimum of two years (mean 40.5 months) and assessed by the Oxford Hip Score, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Short-Form (SF)-12 and patient satisfaction. Co-morbidity, surgical exposure, the Hospital for Special Surgery (HSS) knee scores and the range of movement were also used. A standard medial parapatellar approach was used in 57 patients and the rectus snip in 50. The two groups were equivalent for age, sex and co-morbidity scores. The WOMAC function, pain, stiffness and satisfaction scores demonstrated no statistical difference. The use of a rectus snip as an extensile procedure has no effect on outcome.

Perineural pressures under the pneumatic tourniquet in the upper extremity.

The literature indicates that tourniquet-induced neurological injuries are relatively common and frequently occur at a subclinical level. In order to evaluate the pressure transmitted to the major peripheral nerves of the arm by an externally applied pneumatic tourniquet, a fully implantable biomedical pressure transducer was placed adjacent the radial, median and ulnar nerves in six cadaver upper extremities of average dimensions. This sensor allowed accurate, reproducible measurements of perineural pressures without requiring significant disruption of the normal anatomical structures of the test limb for its installation. At levels of tourniquet cuff inflation which are commonly used in clinical practice, there was little or no decrease in the pressure detected in the perineural regions over that applied to the surface of the limb. In addition, there was a steep gradient of perineural pressure between locations beneath the edge of the cuff and those under its midpoint. This was most marked at the highest levels of tourniquet inflation. At presently accepted levels of inflation, pneumatic tourniquet cuffs transmit high pressures to the peripheral nerves without any significant attenuation by the intervening soft tissues. The distribution of these forces is one which may subject the underlying nerves to deleterious shear forces, especially at higher levels of inflation.

An Adaptive Tourniquet for Improved Safety in Surgery

The increasingly recognized inability of the current generation of pneumatic tourniquets to control pressure with adequate accuracy, reliability, and stability has been associated with continuing reports of tourniquet-related injuries, incidents, and hazards. Moreover, the labor-intensiveness and operating costs associated with the use of current types of pneumatic tourniquets have significant cost implications for hospitals. To a large extent, the recent development of a microprocessor-based tourniquet capable of safely and accurately maintaining a desired pressure, and capable of simultaneously performing other functions such as detection of alarm conditions, has reduced these hazards and operating-cost implications. Furthermore, the availability of a microprocessor-based tourniquet has facilitated the development of the adaptive tourniquet described in this paper, in which the pressure in a tourniquet cuff is changed throughout a surgical procedure as a function of the patients changing intraoperative systolic pressure, thus approximating the minimum safe pressure necessary to maintain a bloodless field for surgery. While the use of an adaptive tourniquet, rather than just a microprocessor-based tourniquet set at a constant pressure may not be necessary in most cases, it promises to have significant value in certain surgical procedures and for patients who may be at greater risk of tourniquet-induced complications. Also, the lower average pressures possible through the use of an adaptive tourniquet may permit the evolution of surgical techniques of longer duration without a concomitant increase in the risk of tourniquet-induced complications.

Anaesthetic management of the patient with rheumatoid arthritis

SummaryRheumatoid arthritis is a relatively common disease for which surgical treatment is being employed with increasing frequency. The improved results are the product of the co-ordinated efforts of many medical and paramedical disciplines. The skill of anaesthetic management is an important contributing factor.From our experiences during the past five years, special problems can be anticipated. These are: airway impairment (secondary to hypoplastic mandible, temporomandibular joint ankylosis, cervical spine restriction, atlanto-axial subluxation, low cervical subluxation, cricoarytenoid arthritis and laryngeal tissue damage); respiratory inadequacy ( rheumatoid lung nodules, chronic lung diffusing interstitial fibrosis, costovertebral joint fixation, and thoracic vertebral fixation deformity); cardiovascular impairment (pericardium, myocardium, coronary artery, regurgitant aortic valve involvement, and disseminated necrotizing arteritis); haemopoietic defects (anaemia, leucopenia, and bleeding tendencies); renal and hepatic dysfunction; drug therapy hazards; problems in posturings; and hazards associated with multiple anaesthetics and surgical procedures.Advanced rheumatoid arthritis is a crippling, incapacitating disease. Corrective surgical procedures offer new hope and great potentiality for its victims. Care in the anaesthetic management of these patients can significantly contribute to the successful outcome of these procedures.

Position of the knee joint after total joint arthroplasty

A method for assessing knee joint position after surgery using the preoperative long-leg radiograph and the postoperative knee radiograph is described. Assessment of the formula has shown a near perfect correlation between the calculated position on the long-leg radiograph compared with the measured position for 44 knees. Three hundred eighteen knees after total joint arthroplasty were retrospectively reviewed and the postoperative position was determined. The preoperative position of the mechanical axis was 14.5 +/- 37.3 mm medial to the knee joint center. Using the standing knee radiograph the postoperative position of the mechanical axis was 3.07 +/- 9.2 mm lateral to the knee joint center, while the portable radiograph placed the mechanical axis 4.5 +/- 12.4 mm medial to the knee joint center. There was a highly significant difference in the position of the knee joint center depending on the radiograph used for calculation (standing or portable). The difference between the two means was not due to opening of the knee joint, but likely due to change in the rotation of the knee in the presence of knee flexion. This series of the knee arthroplasties has a low projected rate of aseptic failure.